This project concerns the interaction of proteins with fluorescent ligands used as probes to study macromolecular structure. Present work includes: l. Binding studies on the interaction of cationic fluorescent dyes with alcohol dehydrogenases and serum albumins. Such dyes appear to bind in areas distinct from those occupied by more commonly used anionic fluorescent probes. 2. Spectral characterization of quinacrine mustard conjugates of proteins in order to establish the usefulness of this dye in protein chemistry as well as nucleic acid and chromosome studies. 3. Preparation and characterization of protein conjugates containing a new dye, N-105, made by Walter Stewart of NIAMDD. The dye is designed for fluorescence microscopic localization of nerve processes following microinjection into the axoplasm of individual nerves.